1. Field of the Invention
The present invention relates to a speech synthesizing method by the segmentation of the linear Formant transition region and more particularly, to a mode to synthesize speech by the combination of a speech coding mode and a Formant analysis mode.
2. Description of the Prior Art
Generally, the mode of speech synthesis is classified into a speech coding mode and a Formant frequency analysis mode. After such a speech coding mode, the speech signal, relating to a whole phoneme including a syllable of the speech or a semi-syllable of the speech, is analyzed by a mode of a linear predictive coding (LPC) or a line spectrum pair (another representation for LPC parameters), and stored in a data base. The speech signal is then extracted from the data base for synthesizing. However, although such a speech coding mode can obtain a better sound quality, it requires an increase of data quantity since the speech signal must be divided into an interval frame (a short-time frame) for analyzing. Thus, there are a number of problems. For example, memory quantity must be increased and processing speed must be slowed down because data must be generated, even if the data is in a region where the frequency characteristics of the speech signal remains unchanged.
Also such a Formant frequency analysis mode is used to extract the basic Formant frequency and the Formant bandwidth, and synthesize the speech corresponding to an arbitrary sound by executing a regulation program after normalizing the change of the Formant frequency, which occurs in conjunction with a phoneme. However, it is difficult to find out the regulation of the change. Further, there exists the problem of slowing down the processing speed since the Formant frequency transition must be processed by a fixed regulation of the change.